eliciting a gag reflex? If not, where are the trigger zones? These are most often the dorsum of the tongue, or the posterior palate.
Ulceration – Are there any existing signs of ulceration, and do they correspond to the extensions of a prosthesis?
Temporomandibular disorder (TMD) – Are there currently any signs of muscle pain or temporomandibular joint (TMJ) derangement?
Candidosis and angular cheilitis – How old are the prostheses and what is the patient's current hygiene regime? Does the patient seem to be over-closed? Is there a high carbohydrate intake throughout the day, nutritional deficiency or a dry mouth?
Dry mouth – Does the patient complain of a dry mouth? Is this medication-induced? You can grade a dry mouth using the Challacombe scale (see recommended reading).
Tori or significantly undercut ridges – If present will these interfere with the denture extensions or path of insertion?
Retained roots – Could these be retained as overdenture abutments?
Any suspicious lesions, particularly for at-risk patients, that should be investigated or monitored alongside treatment?
Ridge assessment
Manual palpation is very important in order to assess the ridges adequately. This includes the ridge form (Figure 4.1) (well-formed, atrophic, rounded, flat, knife-edge, fibrous, undercut) and the proximity of the frenal attachments to the crest of the ridges.
Assessment of existing prostheses
The stability (resistance to horizontal or rotational displacement when fully seated) and retention (resistance to vertical displacement) of each prosthesis should be assessed in turn. It is easier to do this individually rather than having both prostheses in at the same time. The upper should be seated from in front of the patient, and whilst holding the molar units, should be rotated in a horizontal plane. It can then be displaced vertically, ensuring that the patient is not holding the denture in place with their tongue, to assess retention. The lower should also be seated from in front of the patient, ideally with the patient in a seated position. Stability can be assessed as above, but also in an antero-posterior direction by pinching the lower incisors between thumb and forefinger and moving the denture lingually and labially.
The denture extensions should then be considered – labial, buccal and posterior aspects – but also coverage of the tuberosities on the upper and disto-lingual extension on the lower. The anatomy of the denture-bearing area is considered in Chapter 10. It is important to assess the extensions systematically to look for under- or overextension. Direct vision is possible for the lower but it can be more challenging on the upper. Retracting the sulcus with your index finger parallel to the arch means that as you seat the denture, you can feel whether the sulcus is ‘pulled in’ towards the prosthesis. If this is the case, the denture is overextended in this area. It is also possible to take a wash impression in silicone or alginate to assess the denture extensions at this stage.
In terms of aesthetics – lip support, incisal plane and buccal space should be noted. These are considered further in Chapter 20.
Finally, in relation to the occlusion, it is important to note whether the intercuspal position is stable and whether there are any heavy contacts. Is the intercuspal position coincident with the retruded arc of closure – and if not, what are the characteristics of the slide? Finally, assessment should be made of the freeway space between the dentures – although at this stage an estimate can be made by listening to the ‘speaking space’ available – sibilant sounds will sound sharp and whistle-like if the freeway space is restricted, and hollow or absent, if it is excessive.
At this point, a diagnosis can be made with a suitable prognosis (and justification), and your patient's expectations can be discussed in an informed way. A treatment plan can be devised relating to the fitting surface, the occlusal surface and aesthetics (polished surfaces).
5 Edentulous ridge presentations
The photographs opposite show a range of edentulous ridge presentations. Whilst the range shown is by no means exhaustive, each photograph presents a number of interesting points for consideration when planning a removable prosthesis.
Upper edentulous ridges
Photograph 1
Intraoral access here is good and the full denture-bearing area (DBA) can be palpated without any pain or gagging. The mucosa looks moist and there are no signs clinically of a dry mouth. The ridge is well formed with high and rounded ridges – and this would be classified as Class III (Cawood and Howell). A retained root has recently been extracted from the UL5 and this presents as a crestal defect. The prominent incisive papilla is erythematous and this is a sign that it may need a degree of relief in order to prevent recurrent trauma. There is a slight buccal defect to the ridge on the left-hand side and the muscle attachment here inserts into the base of the sulcus. Paradoxically it can be easier to account for high muscle insertions than lower ones – and so this area would receive particular attention during the working impression. It is possible to see the posterior extent of the existing denture, which is short of the fovea palatini by at least 10 mm. It is also possible to see the limited degree to which the denture base wraps around the tuberosity on the right-hand side – and this can be improved during the working impression with a border moulding material to ensure that its full anatomy is captured.
Photograph 2
Intraoral access here is slightly restricted. The full DBA can be palpated without pain or gagging. The mucosa looks shiny and dry, and clinically there are signs of a dry mouth; the mirrors stick to the mucosa, and food debris accumulates at the denture borders. It may be necessary for the patient to consider a saliva substitute in order to promote effective adhesion and cohesion, and a border seal. The ridge is well defined and rounded (Class III), but the sulcal depth reduces significantly towards the posterior aspects. The palate is relatively shallow and broad – shallow ridges and a shallow palate mean that the denture may have a compromised stability. The muscle attachments insert onto the crest of the ridge – this is the other extreme of how attachments may present. The challenge here is ensuring they are accommodated for, without compromising the border seal. The labial portion of the anterior ridge presents with a significant undercut and it is worth considering at the assessment stage whether a defined path of insertion is possible, or whether the permanent base should be modified with permanent soft liner to allow the ridge to be atraumatically engaged.
Photograph 3
Intraoral access here is excellent. Palpation of the DBA in the palate beyond the posterior border of the existing prosthesis results in a gag reflex. There is no pain on palpation. The ridge is well formed (Class III) but lacks some definition in the premolar regions, where it presents with a knife edge (Class IV). Once again, muscle attachments are situated near the base of the sulcus, so attention to detail during the working impression will
